title: Interleukin (IL)-32β-mediated CCAAT/enhancer-binding protein α (C/EBPα) phosphorylation by protein kinase Cδ (PKCδ) abrogates the inhibitory effect of C/EBPα on IL-10 production.
abstract: We previously reported that IL-32β promotes IL-10 production in myeloid cells. However, the underlying mechanism remains elusive. In this study, we demonstrated that IL-32β abrogated the inhibitory effect of CCAAT/enhancer-binding protein α (C/EBPα) on IL-10 expression in U937 cells. We observed that the phosphorylation of C/EBPα Ser-21 was inhibited by a PKCδ-specific inhibitor, rottlerin, or IL-32β knockdown by siRNA and that IL-32β shifted to the membrane from the cytosol upon phorbol 12-myristate 13-acetate treatment. We revealed that IL-32β suppressed the binding of C/EBPα to IL-10 promoter by using ChIP assay. These data suggest that PKCδ and IL-32β may modulate the effect of C/EBPα on IL-10 expression. We next demonstrated by immunoprecipitation that IL-32β interacted with PKCδ and C/EBPα, thereby mediating C/EBPα Ser-21 phosphorylation by PKCδ. We showed that IL-32β suppressed the inhibitory effect of C/EBPα on IL-10 promoter activity. However, the IL-10 promoter activity was reduced to the basal level by rottlerin treatment. When C/EBPα serine 21 was mutated to glycine (S21G), the inhibitory effect of C/EBPα S21G on IL-10 promoter activity was not modulated by IL-32β. Taken together, our results show that IL-32β-mediated C/EBPα Ser-21 phosphorylation by PKCδ suppressed C/EBPα binding to IL-10 promoter, which promoted IL-10 production in U937 cells.
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Korea.
authors.forename: Jeong-Woo
authors.initials: JW
authors.lastname: Kang
authors.forename: Yun Sun
authors.initials: YS
authors.lastname: Park
authors.forename: Man Sub
authors.initials: MS
authors.lastname: Kim
authors.forename: Dong Hun
authors.initials: DH
authors.lastname: Lee
authors.forename: Yesol
authors.initials: Y
authors.lastname: Bak
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Ham
authors.forename: Soo Ho
authors.initials: SH
authors.lastname: Park
authors.forename: Jin Tae
authors.initials: JT
authors.lastname: Hong
authors.forename: Do-Young
authors.initials: DY
authors.lastname: Yoon
mesh_terms: D001483:Base Sequence; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000737:chemistry / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis* / Q000235:genetics; D007378:Interleukins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D051745:Protein Kinase C-delta / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020298:U937 Cells
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; C496971:IL32 protein, human; D007378:Interleukins; D016753:Interleukin-10; D010768:Phosphoserine; D051745:Protein Kinase C-delta; D013755:Tetradecanoylphorbol Acetate
keywords: C/EBP Transcription Factor; Chromatin Immunoprecipitation (ChiP); Gene Regulation; Gene Silencing; Protein Kinase C (PKC); U937